Planktonic Foraminifera in Surface Sediments of the Emperor Seamount Chain (Pacific Ocean)

The fauna of the Emperor Seamount Chain (ESC) is unique in composition and endemic to a certain degree. The isolation of the ESC allows considering them a model region for studying long-term climate changes in the world oceans. We studied planktonic foraminifera (PF) in the surface sediments of the Nintoku, Jingy, Ojin, and Koko guyots located in the southern the ESC (35°–42° N). This area is influenced by the warm North Pacific Current and the transition zone between sub-Arctic and tropical water masses. We identified twenty-three species of PF in the assemblages that include representatives of various climatic groups: polar, subpolar, transitional, subtropical, and tropical. Two discrete upwelling-influenced sites (Nintoku LV86-21 and Koko LV86-5) exhibit exceptionally high PF shell concentrations, indicating elevated biogenic sediment flux and enhanced carbonate preservation under high-productivity conditions. In contrast, station LV86-6 shows advanced carbonate dissolution features, including elevated fragment content and selective enrichment of dissolution-resistant species, confirmed by scanning electron microscopy. These findings demonstrate that sedimentary PF assemblages in the ESC are not simple climate proxies but rather taphonomically modified records shaped by the interplay of biogenic sediment input, hydrodynamic focusing, topography-induced upwelling, and depth-dependent carbonate dissolution.